This invention pertains to a new lithium-containing binder composition suitable for use in bonding a particulate material such as alumina, magnesia, or other aggregate material to make a shaped refractory article.
It is known in the art to employ phenol-formaldehyde resole resins to bond granular refractory material for use in, for example, a foundry molding composition or a refractory article. For example, U.S. Pat. No. 4,426,467 to Quist, et al. discloses such a composition which is curable at room temperature in the presence of an alkali such as sodium or potassium, using a lactone as curing agent. The composition contributes to the dimensional stability of articles produced therefrom via refractory bonding (i.e., through durable carbon-carbon bonds and carbon-aggregate bonds) and also provides abrasion resistance.
It is also known to use a phenol-formaldehyde novolac resin to bond a carbonaceous aggregate as is disclosed in Chandramouli, et al., U.S. Ser. No. 4,775,455, issued Oct. 4, 1988; Chandramouli, et al., U.S. Pat. No. 210,726, filed June 23, 1988; and Gerber U.S. Ser. No. 271447, filed Nov. 15, 1988, titled "Binder Composition Comprising Low Molecular Weight Poly(Orthomethylolated) Phenolic Compound And Novolac Resin" (all assigned to the assignee of the present invention).
Ester curable phenol formaldehyde resole resins are alkaline in nature, i.e., containing potassium or sodium alkali or mixtures thereof. Such resins are disclosed in U.S. Pat. No. 4,474,904 to Lemon, et al. Use of lithium or magnesium salts of lower alkanoic and inorganic acids is known for imparting hot green sand workability in foundry mold applications (see U.S. Pat. No. 4,131,476 to Melcher et al.). Use of lithium ions as the alkalizing agent to facilitate ester cure of resole resins for use in refractory articles is heretofore not demonstrated.